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Zhao K, Zhao P, Wang S, Xia Y, Zhang G. FoldPAthreader: predicting protein folding pathway using a novel folding force field model derived from known protein universe. Genome Biol 2024; 25:152. [PMID: 38862984 PMCID: PMC11167914 DOI: 10.1186/s13059-024-03291-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Accepted: 05/29/2024] [Indexed: 06/13/2024] Open
Abstract
Protein folding has become a tractable problem with the significant advances in deep learning-driven protein structure prediction. Here we propose FoldPAthreader, a protein folding pathway prediction method that uses a novel folding force field model by exploring the intrinsic relationship between protein evolution and folding from the known protein universe. Further, the folding force field is used to guide Monte Carlo conformational sampling, driving the protein chain fold into its native state by exploring potential intermediates. On 30 example targets, FoldPAthreader successfully predicts 70% of the proteins whose folding pathway is consistent with biological experimental data.
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Affiliation(s)
- Kailong Zhao
- College of Information Engineering, Zhejiang University of Technology, HangZhou, 310023, China
| | - Pengxin Zhao
- College of Information Engineering, Zhejiang University of Technology, HangZhou, 310023, China
| | - Suhui Wang
- College of Information Engineering, Zhejiang University of Technology, HangZhou, 310023, China
| | - Yuhao Xia
- College of Information Engineering, Zhejiang University of Technology, HangZhou, 310023, China
| | - Guijun Zhang
- College of Information Engineering, Zhejiang University of Technology, HangZhou, 310023, China.
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2
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Krantz BA. Anthrax Toxin: Model System for Studying Protein Translocation. J Mol Biol 2024; 436:168521. [PMID: 38458604 DOI: 10.1016/j.jmb.2024.168521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 02/08/2024] [Accepted: 03/04/2024] [Indexed: 03/10/2024]
Abstract
Dedicated translocase channels are nanomachines that often, but not always, unfold and translocate proteins through narrow pores across the membrane. Generally, these molecular machines utilize external sources of free energy to drive these reactions, since folded proteins are thermodynamically stable, and once unfolded they contain immense diffusive configurational entropy. To catalyze unfolding and translocate the unfolded state at appreciable timescales, translocase channels often utilize analogous peptide-clamp active sites. Here we describe how anthrax toxin has been used as a biophysical model system to study protein translocation. The tripartite bacterial toxin is composed of an oligomeric translocase channel, protective antigen (PA), and two enzymes, edema factor (EF) and lethal factor (LF), which are translocated by PA into mammalian host cells. Unfolding and translocation are powered by the endosomal proton gradient and are catalyzed by three peptide-clamp sites in the PA channel: the α clamp, the ϕ clamp, and the charge clamp. These clamp sites interact nonspecifically with the chemically complex translocating chain, serve to minimize unfolded state configurational entropy, and work cooperatively to promote translocation. Two models of proton gradient driven translocation have been proposed: (i) an extended-chain Brownian ratchet mechanism and (ii) a proton-driven helix-compression mechanism. These models are not mutually exclusive; instead the extended-chain Brownian ratchet likely operates on β-sheet sequences and the helix-compression mechanism likely operates on α-helical sequences. Finally, we compare and contrast anthrax toxin with other related and unrelated translocase channels.
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Affiliation(s)
- Bryan A Krantz
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, Baltimore, 650 W. Baltimore Street, Baltimore, MD 21201, USA.
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3
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Tessier E, Cheutin L, Garnier A, Vigne C, Tournier JN, Rougeaux C. Early Circulating Edema Factor in Inhalational Anthrax Infection: Does It Matter? Microorganisms 2024; 12:308. [PMID: 38399712 PMCID: PMC10891819 DOI: 10.3390/microorganisms12020308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 01/22/2024] [Accepted: 01/26/2024] [Indexed: 02/25/2024] Open
Abstract
Anthrax toxins are critical virulence factors of Bacillus anthracis and Bacillus cereus strains that cause anthrax-like disease, composed of a common binding factor, the protective antigen (PA), and two enzymatic proteins, lethal factor (LF) and edema factor (EF). While PA is required for endocytosis and activity of EF and LF, several studies showed that these enzymatic factors disseminate within the body in the absence of PA after intranasal infection. In an effort to understand the impact of EF in the absence of PA, we used a fluorescent EF chimera to facilitate the study of endocytosis in different cell lines. Unexpectedly, EF was found inside cells in the absence of PA and showed a pole-dependent endocytosis. However, looking at enzymatic activity, PA was still required for EF to induce an increase in intracellular cAMP levels. Interestingly, the sequential delivery of EF and then PA rescued the rise in cAMP levels, indicating that PA and EF may functionally associate during intracellular trafficking, as well as it did at the cell surface. Our data shed new light on EF trafficking and the potential location of PA and EF association for optimal cytosolic delivery.
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Affiliation(s)
- Emilie Tessier
- Département des Maladies Infectieuses, Institut de Recherche Biomédicale des Armées, 91220 Brétigny-sur-Orge, France (C.R.)
| | - Laurence Cheutin
- Département des Maladies Infectieuses, Institut de Recherche Biomédicale des Armées, 91220 Brétigny-sur-Orge, France (C.R.)
| | - Annabelle Garnier
- Département des Maladies Infectieuses, Institut de Recherche Biomédicale des Armées, 91220 Brétigny-sur-Orge, France (C.R.)
| | - Clarisse Vigne
- Département des Maladies Infectieuses, Institut de Recherche Biomédicale des Armées, 91220 Brétigny-sur-Orge, France (C.R.)
| | - Jean-Nicolas Tournier
- Département des Maladies Infectieuses, Institut de Recherche Biomédicale des Armées, 91220 Brétigny-sur-Orge, France (C.R.)
- Institut Pasteur, 75015 Paris, France
| | - Clémence Rougeaux
- Département des Maladies Infectieuses, Institut de Recherche Biomédicale des Armées, 91220 Brétigny-sur-Orge, France (C.R.)
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4
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Liu A, Zhang H, Zheng Q, Wang S. The Potential of Cyclodextrins as Inhibitors for the BM2 Protein: An In Silico Investigation. Molecules 2024; 29:620. [PMID: 38338365 PMCID: PMC10856705 DOI: 10.3390/molecules29030620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 01/23/2024] [Accepted: 01/26/2024] [Indexed: 02/12/2024] Open
Abstract
The influenza BM2 transmembrane domain (BM2TM), an acid-activated proton channel, is an attractive antiviral target due to its essential roles during influenza virus replication, whereas no effective inhibitors have been reported for BM2. In this study, we draw inspiration from the properties of cyclodextrins (CDs) and hypothesize that CDs of appropriate sizes may possess the potential to act as inhibitors of the BM2TM proton channel. To explore this possibility, molecular dynamics simulations were employed to assess their inhibitory capabilities. Our findings reveal that CD4, CD5, and CD6 are capable of binding to the BM2TM proton channel, resulting in disrupted water networks and reduced hydrogen bond occupancy between H19 and the solvent within the BM2TM channel necessary for proton conduction. Notably, CD4 completely obstructs the BM2TM water channel. Based on these observations, we propose that CD4, CD5, and CD6 individually contribute to diminishing the proton transfer efficiency of the BM2 protein, and CD4 demonstrates promising potential as an inhibitor for the BM2 proton channel.
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Affiliation(s)
- Aijun Liu
- Institute of Theoretical Chemistry, College of Chemistry, Jilin University, Changchun 130023, China; (A.L.); (H.Z.)
| | - Hao Zhang
- Institute of Theoretical Chemistry, College of Chemistry, Jilin University, Changchun 130023, China; (A.L.); (H.Z.)
| | - Qingchuan Zheng
- School of Pharmaceutical Sciences, Jilin University, Changchun, 130021, China
| | - Song Wang
- Institute of Theoretical Chemistry, College of Chemistry, Jilin University, Changchun 130023, China; (A.L.); (H.Z.)
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5
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Papatheodorou P, Minton NP, Aktories K, Barth H. An Updated View on the Cellular Uptake and Mode-of-Action of Clostridioides difficile Toxins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2024; 1435:219-247. [PMID: 38175478 DOI: 10.1007/978-3-031-42108-2_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Research on the human gut pathogen Clostridioides (C.) difficile and its toxins continues to attract much attention as a consequence of the threat to human health posed by hypervirulent strains. Toxin A (TcdA) and Toxin B (TcdB) are the two major virulence determinants of C. difficile. Both are single-chain proteins with a similar multidomain architecture. Certain hypervirulent C. difficile strains also produce a third toxin, namely binary toxin CDT (C. difficile transferase). C. difficile toxins are the causative agents of C. difficile-associated diseases (CDADs), such as antibiotics-associated diarrhea and pseudomembranous colitis. For that reason, considerable efforts have been expended to unravel their molecular mode-of-action and the cellular mechanisms responsible for their uptake. Many of these studies have been conducted in European laboratories. Here, we provide an update on our previous review (Papatheodorou et al. Adv Exp Med Biol, 2018) on important advances in C. difficile toxins research.
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Affiliation(s)
- Panagiotis Papatheodorou
- Institute of Experimental and Clinical Pharmacology, Toxicology and Pharmacology of Natural Products, Ulm University Medical Center, Ulm, Germany.
| | - Nigel P Minton
- BBSRC/EPSRC Synthetic Biology Research Centre, University of Nottingham, Nottingham, UK
| | - Klaus Aktories
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, Freiburg, Germany
| | - Holger Barth
- Institute of Experimental and Clinical Pharmacology, Toxicology and Pharmacology of Natural Products, Ulm University Medical Center, Ulm, Germany
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Zuo W, Tian M, Qi J, Zhang G, Hu J, Wang S, Bao Y. The functions of EF-hand proteins from host and zoonotic pathogens. Microbes Infect 2023:105276. [PMID: 38072184 DOI: 10.1016/j.micinf.2023.105276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 12/05/2023] [Accepted: 12/06/2023] [Indexed: 12/24/2023]
Abstract
EF-hand proteins not only regulate biological processes, but also influence immunity and infection. In this review, we summarize EF-hand proteins' functions in host and zoonotic pathogens, with details in structures, Ca2+ affinity, downstream targets and functional mechanisms. Studies entitled as EF-hand-related but with less solid features were also discussed. We believe it could raise cautions and facilitate proper research strategy for researchers.
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Affiliation(s)
- Wei Zuo
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai 200241, China
| | - Mingxing Tian
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai 200241, China
| | - Jingjing Qi
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai 200241, China
| | - Guangdong Zhang
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai 200241, China
| | - Jiangang Hu
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai 200241, China
| | - Shaohui Wang
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai 200241, China; Engineering Research Center for the Prevention and Control of Animal Original Zoonosis of Fujian Province University, College of Life Science, Longyan University, Longyan, 364012, Fujian, China.
| | - Yanqing Bao
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai 200241, China; Engineering Research Center for the Prevention and Control of Animal Original Zoonosis of Fujian Province University, College of Life Science, Longyan University, Longyan, 364012, Fujian, China.
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7
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Liang T, Chen J, Rui Y, Hexi L. The designation, synthesis, and affinity determination of affinity peptide for anthrax protective antigen. Chem Biol Drug Des 2023; 102:669-675. [PMID: 37286890 DOI: 10.1111/cbdd.14280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2023] [Revised: 05/04/2023] [Accepted: 05/26/2023] [Indexed: 06/09/2023]
Abstract
Detection of anthrax protective antigen is an effective way to diagnose anthracnose, and it plays an important part in the treatment of anthracnose. Affinity peptides, as a miniature biological recognition element, can quickly and effectively detect anthrax protective antigens. Based on computer-aided design technology (CAD), we have herein developed an affinity peptide design strategy for the detection of anthrax protective antigens. Firstly, six high-value mutation sites were determined based on the molecular docking between the template peptide and the receptor, and then the multi-site mutation of amino acids was carried out in order to establish a virtual peptide library. The library was selected by using molecular dynamics simulation and the best designed affinity peptide (code: P24) was found. The theoretical affinity with P24 peptide has increased by 19.8% compared with template peptide. Finally, the affinity with P24 peptide was measured by SPR technology to reach the nanomole level, which verified the effectiveness of the design strategy. The newly designed affinity peptide is expected to be used in the diagnosis of anthracnose.
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Affiliation(s)
- Ting Liang
- The Institute of NBC Defense PLA Army, Beijing, China
| | - Jingfei Chen
- The Institute of NBC Defense PLA Army, Beijing, China
- Unit No. 32169 of PLA, Tibet, China
| | - Yan Rui
- The Institute of NBC Defense PLA Army, Beijing, China
| | - Li Hexi
- Unit No. 31666 of PLA, Wuwei, Gansu, China
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Heber S, Borho J, Stadler N, Wondany F, König I, Michaelis J, Papatheodorou P, Barth H, Fellermann M. The Clostridium botulinum C2 Toxin Subunit C2IIa Delivers Enzymes with Positively Charged N-Termini into the Cytosol of Target Cells. Toxins (Basel) 2023; 15:390. [PMID: 37368691 DOI: 10.3390/toxins15060390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 06/05/2023] [Accepted: 06/07/2023] [Indexed: 06/29/2023] Open
Abstract
The binary Clostridium (C.) botulinum C2 toxin consists of two non-linked proteins. The proteolytically activated binding/transport subunit C2IIa forms barrel-shaped homoheptamers, which bind to cell surface receptors, mediate endocytosis, and translocate the enzyme subunit C2I into the cytosol of target cells. Here, we investigate whether C2IIa can be harnessed as a transporter for proteins/enzymes fused to polycationic tags, as earlier demonstrated for the related anthrax toxin transport subunit PA63. To test C2IIa-mediated transport in cultured cells, reporter enzymes are generated by fusing different polycationic tags to the N- or C-terminus of other bacterial toxins' catalytic A subunits. C2IIa as well as PA63 deliver N-terminally polyhistidine-tagged proteins more efficiently compared to C-terminally tagged ones. However, in contrast to PA63, C2IIa does not efficiently deliver polylysine-tagged proteins into the cytosol of target cells. Moreover, untagged enzymes with a native cationic N-terminus are efficiently transported by both C2IIa and PA63. In conclusion, the C2IIa-transporter serves as a transport system for enzymes that harbor positively charged amino acids at their N-terminus. The charge distribution at the N-terminus of cargo proteins and their ability to unfold in the endosome and subsequently refold in the cytosol determine transport feasibility and efficiency.
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Affiliation(s)
- Sebastian Heber
- Institute of Experimental and Clinical Pharmacology, Toxicology and Pharmacology of Natural Products, Ulm University Medical Center, 89081 Ulm, Germany
| | - Joscha Borho
- Institute of Experimental and Clinical Pharmacology, Toxicology and Pharmacology of Natural Products, Ulm University Medical Center, 89081 Ulm, Germany
| | - Nicole Stadler
- Institute of Experimental and Clinical Pharmacology, Toxicology and Pharmacology of Natural Products, Ulm University Medical Center, 89081 Ulm, Germany
| | - Fanny Wondany
- Institute of Biophysics, Ulm University, 89081 Ulm, Germany
| | - Irina König
- Institute of Experimental and Clinical Pharmacology, Toxicology and Pharmacology of Natural Products, Ulm University Medical Center, 89081 Ulm, Germany
| | - Jens Michaelis
- Institute of Biophysics, Ulm University, 89081 Ulm, Germany
| | - Panagiotis Papatheodorou
- Institute of Experimental and Clinical Pharmacology, Toxicology and Pharmacology of Natural Products, Ulm University Medical Center, 89081 Ulm, Germany
| | - Holger Barth
- Institute of Experimental and Clinical Pharmacology, Toxicology and Pharmacology of Natural Products, Ulm University Medical Center, 89081 Ulm, Germany
| | - Maximilian Fellermann
- Institute of Experimental and Clinical Pharmacology, Toxicology and Pharmacology of Natural Products, Ulm University Medical Center, 89081 Ulm, Germany
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Beitzinger C, Kronhardt A, Benz R. Chloroquine-analogues block anthrax protective antigen channels in steady-state and kinetic studies. Toxicology 2023; 492:153547. [PMID: 37201861 DOI: 10.1016/j.tox.2023.153547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 05/11/2023] [Accepted: 05/15/2023] [Indexed: 05/20/2023]
Abstract
The tripartite anthrax toxin from Bacillus anthracis represents the prototype of A-B type of toxins, where the effector A (an enzymatic subunit) is transported with the help of a binding component B into a target cell. Anthrax toxin consists of three different molecules, two effectors, lethal factor (LF) and edema factor (EF) and the binding component also known as protective antigen (PA). PA forms heptamers or octamers following binding to host cell's receptors and mediates the translocation of the effectors into the cytosol via the endosomal pathway. The cation-selective PA63-channel is able to reconstitute in lipid membranes and can be blocked by chloroquine and other heterocyclic compounds. This suggests that the PA63-channel contains a binding site for quinolines. In this study, we investigated the structure-function relationship of different quinolines for the block of the PA63-channel. The affinity of the different chloroquine analogues to the PA63-channel as provided by the equilibrium dissociation constant was measured using titrations. Some quinolines had a much higher affinity to the PA63-channel than chloroquine itself. We also performed ligand-induced current noise measurements using fast Fourier transformation to get insight in the kinetics of the binding of some quinolines to the PA63-channel. The on-rate constants of ligand binding were around 108M-1·s-1 at 150mM KCl and were only little dependent on the individual quinoline. The off-rates varied between 4s-1 and 160s-1 and depended much more on the structure of the molecules than the on-rate constants. The possible use of the 4-aminoquinolines as a therapy is discussed.
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Affiliation(s)
- Christoph Beitzinger
- Rudolf Virchow Center, Research Center for Experimental Biomedicine, University of Würzburg, Versbacher Straße 9, 97078 Würzburg, Germany
| | - Angelika Kronhardt
- Rudolf Virchow Center, Research Center for Experimental Biomedicine, University of Würzburg, Versbacher Straße 9, 97078 Würzburg, Germany
| | - Roland Benz
- Science Faculty, Constructor University Bremen, Campus-Ring 1, 28759 Bremen, Germany.
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Sharma S, Bahl V, Srivastava G, Shamim R, Bhatnagar R, Gaur D. Recombinant full-length Bacillus Anthracis protective antigen and its 63 kDa form elicits protective response in formulation with addavax. Front Immunol 2023; 13:1075662. [PMID: 36713362 PMCID: PMC9877290 DOI: 10.3389/fimmu.2022.1075662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Accepted: 12/16/2022] [Indexed: 01/14/2023] Open
Abstract
Introduction Bacillus anthracis is the causative agent for the lethal disease anthrax, primarily affecting animals and humans in close contact with an infected host. The pathogenicity of B. anthracis is attributed to the secreted exotoxins and their outer capsule. The host cell-binding exotoxin component "protective antigen" (PA) is reported to be a potent vaccine candidate. The aim of our study is to produce several PA constructs and analyze their vaccine potential. Methods We have designed the various subunit, PA-based recombinant proteins, i.e., full-length Protective antigen (PA-FL), C-terminal 63 kDa fragment (PA63), Protective antigen domain 1-domain 4 chimeras (PA-D1-4) and protective antigen domain 4 (PA-D4) and analyzed their vaccine potential with different human-compatible adjuvants in the mouse model. We have optimized the process and successfully expressed our recombinant antigens as soluble proteins, except full-length PA. All the recombinant antigen formulations with three different adjuvants i.e., Addavax, Alhydrogel, and Montanide ISA 720, were immunized in different mouse groups. The vaccine efficacy of the formulations was analyzed by mouse serum antigen-specific antibody titer, toxin neutralization assay, and survival analysis of mouse groups challenged with a lethal dose of B. anthracis virulent spores. Results We have demonstrated that the PA-FL addavax and PA63 addavax formulations were most effective in protecting spore-challenged mice and serum from the mice immunized with PAFL addavax, PA-FL alhydrogel, PA63 addavax, and PA63 alhydrogel formulations were equivalently efficient in neutralizing the anthrax lethal toxin. The higher levels of serum Th1, Th2, and Th17 cytokines in PA-FL addavax immunized mice correspond to the enhanced protection provided by the formulation in challenged mice. Discussion We have demonstrated that the PA-FL addavax and PA63 addavax formulations exhibit equivalent efficiency as vaccine formulation both in a mouse model of anthrax and mammalian cell lines. However, PA63 is a smaller antigen than PA-FL and more importantly, PA63 is expressed as a soluble protein in E. coli, which imparts a translational advantage to PA63-based formulation. Thus, the outcome of our study has significant implications for the development of protective antigen-based vaccine formulations for human use against the lethal disease anthrax.
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Affiliation(s)
- Shikhar Sharma
- Laboratory of Malaria & Vaccine Research, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India,Department of Oncology Science, University of Oklahoma Health Science Center, Oklahoma City, OK, United States,*Correspondence: Shikhar Sharma, ;
| | - Vanndita Bahl
- Laboratory of Malaria & Vaccine Research, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India
| | - Gaurav Srivastava
- Food Technology Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India
| | - Risha Shamim
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Rakesh Bhatnagar
- Molecular Biology and Genetic Engineering Laboratory, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India
| | - Deepak Gaur
- Laboratory of Malaria & Vaccine Research, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India
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Boyer AE, Gallegos-Candela M, Lins RC, Solano MI, Woolfitt AR, Lee JS, Sanford DC, Knostman KAB, Quinn CP, Hoffmaster AR, Pirkle JL, Barr JR. Comprehensive characterization of toxins during progression of inhalation anthrax in a non-human primate model. PLoS Pathog 2022; 18:e1010735. [PMID: 36534695 PMCID: PMC9810172 DOI: 10.1371/journal.ppat.1010735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Revised: 01/03/2023] [Accepted: 11/28/2022] [Indexed: 12/23/2022] Open
Abstract
Inhalation anthrax has three clinical stages: early-prodromal, intermediate-progressive, and late-fulminant. We report the comprehensive characterization of anthrax toxins, including total protective antigen (PA), total lethal factor (LF), total edema factor (EF), and their toxin complexes, lethal toxin and edema toxin in plasma, during the course of inhalation anthrax in 23 cynomolgus macaques. The toxin kinetics were predominantly triphasic with an early rise (phase-1), a plateau/decline (phase-2), and a final rapid rise (phase-3). Eleven animals had shorter survival times, mean±standard deviation of 58.7±7.6 hours (fast progression), 11 animals had longer survival times, 113±34.4 hours (slow progression), and one animal survived. Median (lower-upper quartile) LF levels at the end-of-phase-1 were significantly higher in animals with fast progression [138 (54.9-326) ng/mL], than in those with slow progression [23.8 (15.6-26.3) ng/mL] (p = 0.0002), and the survivor (11.1 ng/mL). The differences were also observed for other toxins and bacteremia. Animals with slow progression had an extended phase-2 plateau, with low variability of LF levels across all time points and animals. Characterization of phase-2 toxin levels defined upper thresholds; critical levels for exiting phase-2 and entering the critical phase-3, 342 ng/mL (PA), 35.8 ng/mL (LF), and 1.10 ng/mL (EF). The thresholds were exceeded earlier in animals with fast progression (38.5±7.4 hours) and later in animals with slow progression (78.7±15.2 hours). Once the threshold was passed, toxin levels rose rapidly in both groups to the terminal stage. The time from threshold to terminal was rapid and similar; 20.8±7.4 hours for fast and 19.9±7.5 hours for slow progression. The three toxemic phases were aligned with the three clinical stages of anthrax for fast and slow progression which showed that anthrax progression is toxin- rather than time-dependent. This first comprehensive evaluation of anthrax toxins provides new insights into disease progression.
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Affiliation(s)
- Anne E. Boyer
- Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
- * E-mail:
| | | | - Renato C. Lins
- Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
- Battelle Atlanta Analytical Services, Atlanta, Georgia, United States of America
| | - Maria I. Solano
- Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Adrian R. Woolfitt
- Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - John S. Lee
- Biomedical Advanced Research and Development Authority, Washington, DC, United States of America
| | - Daniel C. Sanford
- Battelle Biomedical Research Center, West Jefferson, Ohio, United States of America
| | | | - Conrad P. Quinn
- Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Alex R. Hoffmaster
- Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - James L. Pirkle
- Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - John R. Barr
- Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
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Holay M, Krishnan N, Zhou J, Duan Y, Guo Z, Gao W, Fang RH, Zhang L. Single Low-Dose Nanovaccine for Long-Term Protection against Anthrax Toxins. NANO LETTERS 2022; 22:9672-9678. [PMID: 36448694 PMCID: PMC9970955 DOI: 10.1021/acs.nanolett.2c03881] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Anthrax infections caused by Bacillus anthracis are an ongoing bioterrorism and livestock threat worldwide. Current approaches for management, including extended passive antibody transfusion, antibiotics, and prophylactic vaccination, are often cumbersome and associated with low patient compliance. Here, we report on the development of an adjuvanted nanotoxoid vaccine based on macrophage membrane-coated nanoparticles bound with anthrax toxins. This design leverages the natural binding interaction of protective antigen, a key anthrax toxin, with macrophages. In a murine model, a single low-dose vaccination with the nanotoxoids generates long-lasting immunity that protects against subsequent challenge with anthrax toxins. Overall, this work provides a new approach to address the ongoing threat of anthrax outbreaks and bioterrorism by taking advantage of an emerging biomimetic nanotechnology.
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Mondal AK, Lata K, Singh M, Chatterjee S, Chauhan A, Puravankara S, Chattopadhyay K. Cryo-EM elucidates mechanism of action of bacterial pore-forming toxins. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:184013. [PMID: 35908609 DOI: 10.1016/j.bbamem.2022.184013] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 07/05/2022] [Accepted: 07/20/2022] [Indexed: 06/15/2023]
Abstract
Pore-forming toxins (PFTs) rupture plasma membranes and kill target cells. PFTs are secreted as soluble monomers that undergo drastic structural rearrangements upon interacting with the target membrane and generate transmembrane oligomeric pores. A detailed understanding of the molecular mechanisms of the pore-formation process remains unclear due to limited structural insights regarding the transmembrane oligomeric pore states of the PFTs. However, recent advances in the field of cryo-electron microscopy (cryo-EM) have led to the high-resolution structure determination of the oligomeric pore forms of diverse PFTs. Here, we discuss the pore-forming mechanisms of various PFTs, specifically the mechanistic details contributed by the cryo-EM-based structural studies.
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Affiliation(s)
- Anish Kumar Mondal
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, SAS Nagar, Manauli, Mohali 140306, Punjab, India
| | - Kusum Lata
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, SAS Nagar, Manauli, Mohali 140306, Punjab, India
| | - Mahendra Singh
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, SAS Nagar, Manauli, Mohali 140306, Punjab, India
| | - Shamaita Chatterjee
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, SAS Nagar, Manauli, Mohali 140306, Punjab, India
| | - Aakanksha Chauhan
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, SAS Nagar, Manauli, Mohali 140306, Punjab, India
| | - Sindhoora Puravankara
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, SAS Nagar, Manauli, Mohali 140306, Punjab, India
| | - Kausik Chattopadhyay
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, SAS Nagar, Manauli, Mohali 140306, Punjab, India.
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14
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Ascough S, Ingram RJ, Chu KKY, Moore SJ, Gallagher T, Dyson H, Doganay M, Metan G, Ozkul Y, Baillie L, Williamson ED, Robinson JH, Maillere B, Boyton RJ, Altmann DM. Impact of HLA Polymorphism on the Immune Response to Bacillus Anthracis Protective Antigen in Vaccination versus Natural Infection. Vaccines (Basel) 2022; 10:vaccines10101571. [PMID: 36298436 PMCID: PMC9610610 DOI: 10.3390/vaccines10101571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 09/07/2022] [Accepted: 09/14/2022] [Indexed: 11/16/2022] Open
Abstract
The causative agent of anthrax, Bacillus anthracis, evades the host immune response and establishes infection through the production of binary exotoxins composed of Protective Antigen (PA) and one of two subunits, lethal factor (LF) or edema factor (EF). The majority of vaccination strategies have focused upon the antibody response to the PA subunit. We have used a panel of humanised HLA class II transgenic mouse strains to define HLA-DR-restricted and HLA-DQ-restricted CD4+ T cell responses to the immunodominant epitopes of PA. This was correlated with the binding affinities of epitopes to HLA class II molecules, as well as the responses of two human cohorts: individuals vaccinated with the Anthrax Vaccine Precipitated (AVP) vaccine (which contains PA and trace amounts of LF), and patients recovering from cutaneous anthrax infections. The infected and vaccinated cohorts expressing different HLA types were found to make CD4+ T cell responses to multiple and diverse epitopes of PA. The effects of HLA polymorphism were explored using transgenic mouse lines, which demonstrated differential susceptibility, indicating that HLA-DR1 and HLA-DQ8 alleles conferred protective immunity relative to HLA-DR15, HLA-DR4 and HLA-DQ6. The HLA transgenics enabled a reductionist approach, allowing us to better define CD4+ T cell epitopes. Appreciating the effects of HLA polymorphism on the variability of responses to natural infection and vaccination is vital in planning protective strategies against anthrax.
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Affiliation(s)
- Stephanie Ascough
- Faculty of Medicine, Imperial College, London W12 0NN, UK
- Correspondence: (S.A.); (D.M.A.)
| | - Rebecca J. Ingram
- Wellcome-Wolfson Institute of Experimental Medicine, Queen’s University Belfast, Belfast BT7 1NN, UK
| | | | | | - Theresa Gallagher
- BioMET, School of Medicine, University of Maryland, Baltimore, MD 21201, USA
| | - Hugh Dyson
- Defence Science Technology Laboratory, Porton Down, Salisbury SP4 0JQ, UK
| | - Mehmet Doganay
- Department of Medical Genetics, Erciyes University Hospital, Kayseri 38095, Turkey
| | - Gökhan Metan
- Department of Infectious Diseases and Clinical Microbiology, Hacettepe University Faculty of Medicine Ankara, Ankara 06000, Turkey
| | - Yusuf Ozkul
- Department of Medical Genetics, Erciyes University Hospital, Kayseri 38095, Turkey
| | - Les Baillie
- School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Cardiff CF24 4HQ, UK
| | | | - John H. Robinson
- Institute for Cellular Medicine, Newcastle University, Newcastle upon Tyne NE1 7RU, UK
| | - Bernard Maillere
- CEA-Saclay, Département Médicaments et Technologies pour la Santé, Université Paris-Saclay, 91192 Gif-sur-Yvette, France
| | - Rosemary J. Boyton
- Faculty of Medicine, Imperial College, London W12 0NN, UK
- Lung Division, Royal Brompton and Harefield Hospitals, Guy’s and St Thomas’ NHS Foundation Trust, London SE1 9RT, UK
| | - Daniel M. Altmann
- Faculty of Medicine, Imperial College, London W12 0NN, UK
- Correspondence: (S.A.); (D.M.A.)
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15
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Scott H, Huang W, Andra K, Mamillapalli S, Gonti S, Day A, Zhang K, Mehzabeen N, Battaile KP, Raju A, Lovell S, Bann JG, Taylor DJ. Structure of the anthrax protective antigen D425A dominant negative mutant reveals a stalled intermediate state of pore maturation. J Mol Biol 2022; 434:167548. [PMID: 35304125 DOI: 10.1016/j.jmb.2022.167548] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 03/01/2022] [Accepted: 03/10/2022] [Indexed: 10/18/2022]
Abstract
The tripartite protein complex produced by anthrax bacteria (Bacillus anthracis) is a member of the AB family of β-barrel pore-forming toxins. The protective antigen (PA) component forms an oligomeric prepore that assembles on the host cell surface and serves as a scaffold for binding of lethal and edema factors. Following endocytosis, the acidic environment of the late endosome triggers a pH-induced conformational rearrangement to promote maturation of the PA prepore to a functional, membrane spanning pore that facilitates delivery of lethal and edema factors to the cytosol of the infected host. Here, we show that the dominant-negative D425A mutant of PA stalls anthrax pore maturation in an intermediate state at acidic pH. Our 2.7 Å cryo-EM structure of the intermediate state reveals structural rearrangements that involve constriction of the oligomeric pore combined with an intramolecular dissociation of the pore-forming module. In addition to defining the early stages of anthrax pore maturation, the structure identifies asymmetric conformational changes in the oligomeric pore that are influenced by the precise configuration of adjacent protomers.
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Affiliation(s)
- Harry Scott
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Wei Huang
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Kiran Andra
- Department of Chemistry, Wichita State University, Wichita, KS 67260, USA
| | | | - Srinivas Gonti
- Department of Chemistry, Wichita State University, Wichita, KS 67260, USA
| | - Alexander Day
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Kaiming Zhang
- Stanford Linear Accelerator Center and the Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - Nurjahan Mehzabeen
- Protein Structure Laboratory, University of Kansas, Lawrence, KS 66047, USA
| | - Kevin P Battaile
- IMCA-CAT, APS, Argonne National Laboratory, 9700 South Cass Avenue, Building 435A, Argonne, IL 60439, USA
| | - Anjali Raju
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Scott Lovell
- Protein Structure Laboratory, University of Kansas, Lawrence, KS 66047, USA
| | - James G Bann
- Department of Chemistry, Wichita State University, Wichita, KS 67260, USA.
| | - Derek J Taylor
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH 44106, USA; Department of Biochemistry, Case Western Reserve University, Cleveland, OH 44106, USA.
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16
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Ali Dahhas M, Alsenaidy MA. Role of site-directed mutagenesis and adjuvants in the stability and potency of anthrax protective antigen. Saudi Pharm J 2022; 30:595-604. [PMID: 35693445 PMCID: PMC9177452 DOI: 10.1016/j.jsps.2022.02.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2022] [Accepted: 02/21/2022] [Indexed: 11/03/2022] Open
Abstract
Anthrax is a zoonotic infection caused by the gram-positive, aerobic, spore-forming bacterium Bacillus anthracis. Depending on the origin of the infection, serious health problems or mortality is possible. The virulence of B. anthracis is reliant on three pathogenic factors, which are secreted upon infection: protective antigen (PA), lethal factor (LF), and edema factor (EF). Systemic illness results from LF and EF entering cells through the formation of a complex with the heptameric form of PA, bound to the membrane of infected cells through its receptor. The currently available anthrax vaccines have multiple drawbacks, and recombinant PA is considered a promising second-generation vaccine candidate. However, the inherent chemical instability of PA through Asn deamidation at multiple sites prevents its use after long-term storage owing to loss of potency. Moreover, there is a distinct possibility of B. anthracis being used as a bioweapon; thus, the developed vaccine should remain efficacious and stable over the long-term. Second-generation anthrax vaccines with appropriate adjuvant formulations for enhanced immunogenicity and safety are desired. In this article, using protein engineering approaches, we have reviewed the stabilization of anthrax vaccine candidates that are currently licensed or under preclinical and clinical trials. We have also proposed a formulation to enhance recombinant PA vaccine potency via adjuvant formulation.
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17
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Kouadio JL, Zheng M, Aikins M, Duda D, Duff S, Chen D, Zhang J, Milligan J, Taylor C, Mamanella P, Rydel T, Kessenich C, Panosian T, Yin Y, Moar W, Giddings K, Park Y, Jerga A, Haas J. Structural and functional insights into the first Bacillus thuringiensis vegetative insecticidal protein of the Vpb4 fold, active against western corn rootworm. PLoS One 2021; 16:e0260532. [PMID: 34928980 PMCID: PMC8687597 DOI: 10.1371/journal.pone.0260532] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 11/11/2021] [Indexed: 01/09/2023] Open
Abstract
The western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte, is a major maize pest in the United States causing significant economic loss. The emergence of field-evolved resistant WCR to Bacillus thuringiensis (Bt) traits has prompted the need to discover and deploy new insecticidal proteins in transgenic maize. In the current study we determined the crystal structure and mode of action (MOA) of the Vpb4Da2 protein (formerly known as Vip4Da2) from Bt, the first identified insecticidal Vpb4 protein with commercial level control against WCR. The Vpb4Da2 structure exhibits a six-domain architecture mainly comprised of antiparallel β-sheets organized into β-sandwich layers. The amino-terminal domains 1-3 of the protein share structural homology with the protective antigen (PA) PA14 domain and encompass a long β-pore forming loop as in the clostridial binary-toxB module. Domains 5 and 6 at the carboxyl-terminal half of Vpb4Da2 are unique as this extension is not observed in PA or any other structurally-related protein other than Vpb4 homologs. These unique Vpb4 domains adopt the topologies of carbohydrate-binding modules known to participate in receptor-recognition. Functional assessment of Vpb4Da2 suggests that domains 4-6 comprise the WCR receptor binding region and are key in conferring the observed insecticidal activity against WCR. The current structural analysis was complemented by in vitro and in vivo characterizations, including immuno-histochemistry, demonstrating that Vpb4Da2 follows a MOA that is consistent with well-characterized 3-domain Bt insecticidal proteins despite significant structural differences.
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Affiliation(s)
| | - Meiying Zheng
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Michael Aikins
- Department of Entomology, Kansas State University, Manhattan, Kansas, United States of America
| | - David Duda
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Stephen Duff
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Danqi Chen
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Jun Zhang
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Jason Milligan
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Christina Taylor
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | | | - Timothy Rydel
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Colton Kessenich
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Timothy Panosian
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Yong Yin
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - William Moar
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Kara Giddings
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Yoonseong Park
- Department of Entomology, Kansas State University, Manhattan, Kansas, United States of America
| | - Agoston Jerga
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Jeffrey Haas
- Bayer Crop Science, Chesterfield, Missouri, United States of America
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18
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Solution Structures of Bacillus anthracis Protective Antigen Proteins Using Small Angle Neutron Scattering and Protective Antigen 63 Ion Channel Formation Kinetics. Toxins (Basel) 2021; 13:toxins13120888. [PMID: 34941724 PMCID: PMC8708185 DOI: 10.3390/toxins13120888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 12/03/2021] [Accepted: 12/06/2021] [Indexed: 11/17/2022] Open
Abstract
We are studying the structures of bacterial toxins that form ion channels and enable macromolecule transport across membranes. For example, the crystal structure of the Staphylococcus aureus α-hemolysin (α-HL) channel in its functional state was confirmed using neutron reflectometry (NR) with the protein reconstituted in membranes tethered to a solid support. This method, which provides sub-nanometer structural information, could also test putative structures of the Bacillus anthracis protective antigen 63 (PA63) channel, locate where B. anthracis lethal factor and edema factor toxins (LF and EF, respectively) bind to it, and determine how certain small molecules can inhibit the interaction of LF and EF with the channel. We report here the solution structures of channel-forming PA63 and its precursor PA83 (which does not form channels) obtained with small angle neutron scattering. At near neutral pH, PA83 is a monomer and PA63 a heptamer. The latter is compared to two cryo-electron microscopy structures. We also show that although the α-HL and PA63 channels have similar structural features, unlike α-HL, PA63 channel formation in lipid bilayer membranes ceases within minutes of protein addition, which currently precludes the use of NR for elucidating the interactions between PA63, LF, EF, and potential therapeutic agents.
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19
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Sequence Variability of pXO1-Located Pathogenicity Genes of Bacillus anthracis Natural Strains of Different Geographic Origin. Pathogens 2021; 10:pathogens10121556. [PMID: 34959512 PMCID: PMC8703917 DOI: 10.3390/pathogens10121556] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 11/11/2021] [Accepted: 11/26/2021] [Indexed: 11/18/2022] Open
Abstract
The main pathogenic factor of Bacillus anthracis is a three-component toxin encoded by the pagA, lef, and cya genes, which are located on the pXO1 plasmid. The atxA gene, which encodes the primary regulator of pathogenicity factor expression, is located on the same plasmid. In this work, we evaluated the polymorphism of the pagA, lef, cya, and atxA genes for 85 B. anthracis strains from different evolutionary lineages and canSNP groups. We have found a strong correlation of 19 genotypes with the main evolutionary lineages, but the correlation with the canSNP group of the strain was not as strong. We have detected several genetic markers indicating the geographical origin of the strains, for example, their source from the steppe zone of the former USSR. We also found that strains of the B.Br.001/002 group caused an anthrax epidemic in Russia in 2016 and strains isolated during paleontological excavations in the Russian Arctic have the same genotype as the strains of the B.Br.CNEVA group circulating in Central Europe. This data could testify in favor of the genetic relationship of these two groups of strains and hypothesize the ways of distribution of their ancestral forms between Europe and the Arctic.
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20
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Willaert RG, Kayacan Y, Devreese B. The Flo Adhesin Family. Pathogens 2021; 10:pathogens10111397. [PMID: 34832553 PMCID: PMC8621652 DOI: 10.3390/pathogens10111397] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Revised: 10/11/2021] [Accepted: 10/25/2021] [Indexed: 12/14/2022] Open
Abstract
The first step in the infection of fungal pathogens in humans is the adhesion of the pathogen to host tissue cells or abiotic surfaces such as catheters and implants. One of the main players involved in this are the expressed cell wall adhesins. Here, we review the Flo adhesin family and their involvement in the adhesion of these yeasts during human infections. Firstly, we redefined the Flo adhesin family based on the domain architectures that are present in the Flo adhesins and their functions, and set up a new classification of Flo adhesins. Next, the structure, function, and adhesion mechanisms of the Flo adhesins whose structure has been solved are discussed in detail. Finally, we identified from Pfam database datamining yeasts that could express Flo adhesins and are encountered in human infections and their adhesin architectures. These yeasts are discussed in relation to their adhesion characteristics and involvement in infections.
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Affiliation(s)
- Ronnie G. Willaert
- Research Group Structural Biology Brussels (SBB), Vrije Universiteit Brussel (VUB), 1050 Brussels, Belgium;
- Alliance Research Group VUB-UGent NanoMicrobiology (NAMI), 1050 Brussels, Belgium;
- International Joint Research Group VUB-EPFL NanoBiotechnology & NanoMedicine (NANO), Vrije Universiteit Brussel (VUB), 1050 Brussels, Belgium
- Correspondence: ; Tel.: +32-2629-1846
| | - Yeseren Kayacan
- Research Group Structural Biology Brussels (SBB), Vrije Universiteit Brussel (VUB), 1050 Brussels, Belgium;
- Alliance Research Group VUB-UGent NanoMicrobiology (NAMI), 1050 Brussels, Belgium;
- International Joint Research Group VUB-EPFL NanoBiotechnology & NanoMedicine (NANO), Vrije Universiteit Brussel (VUB), 1050 Brussels, Belgium
- Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Bart Devreese
- Alliance Research Group VUB-UGent NanoMicrobiology (NAMI), 1050 Brussels, Belgium;
- International Joint Research Group VUB-EPFL NanoBiotechnology & NanoMedicine (NANO), Vrije Universiteit Brussel (VUB), 1050 Brussels, Belgium
- Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
- Laboratory for Microbiology, Gent University (UGent), 9000 Gent, Belgium
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21
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Romanenko YO, Riabko AK, Marin MA, Kartseva AS, Silkina MV, Shemyakin IG, Firstova VV. Mechanism of Action of Monoclonal Antibodies That Block the Activity of the Lethal Toxin of Bacillus Anthracis. Acta Naturae 2021; 13:98-104. [PMID: 35127153 PMCID: PMC8807536 DOI: 10.32607/actanaturae.11387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 03/22/2021] [Indexed: 11/20/2022] Open
Abstract
Neutralization of the lethal toxin of Bacillus anthracis is an important topic of both fundamental medicine and practical health care, regarding the fight against highly dangerous infections. We have generated a neutralizing monoclonal antibody 1E10 against the lethal toxin of Bacillus anthracis and described the stages of receptor interaction between the protective antigen (PA) and the surface of eukaryotic cells, the formation of PA oligomers, assembly of the lethal toxin (LT), and its translocation by endocytosis into the eukaryotic cell, followed by the formation of a true pore and the release of LT into the cell cytosol. The antibody was shown to act selectively at the stage of interaction between Bacillus anthracis and the eukaryotic cell, and the mechanism of toxin-neutralizing activity of the 1E10 antibody was revealed. The interaction between the 1E10 monoclonal antibody and PA was found to lead to inhibition of the enzymatic activity of the lethal factor (LF), most likely due to a disruption of true pore formation by PA, which blocks the release of LF into the cytosol.
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Affiliation(s)
- Ya. O. Romanenko
- Federal Budget Institution of Science State Research Center for Applied Microbiology and Biotechnology of Rospotrebnadzor, Obolensk, Moscow Region, 142279 Russia
| | - A. K. Riabko
- Federal Budget Institution of Science State Research Center for Applied Microbiology and Biotechnology of Rospotrebnadzor, Obolensk, Moscow Region, 142279 Russia
| | - M. A. Marin
- Federal Budget Institution of Science State Research Center for Applied Microbiology and Biotechnology of Rospotrebnadzor, Obolensk, Moscow Region, 142279 Russia
| | - A. S. Kartseva
- Federal Budget Institution of Science State Research Center for Applied Microbiology and Biotechnology of Rospotrebnadzor, Obolensk, Moscow Region, 142279 Russia
| | - M. V. Silkina
- Federal Budget Institution of Science State Research Center for Applied Microbiology and Biotechnology of Rospotrebnadzor, Obolensk, Moscow Region, 142279 Russia
| | - I. G. Shemyakin
- Federal Budget Institution of Science State Research Center for Applied Microbiology and Biotechnology of Rospotrebnadzor, Obolensk, Moscow Region, 142279 Russia
| | - V. V. Firstova
- Federal Budget Institution of Science State Research Center for Applied Microbiology and Biotechnology of Rospotrebnadzor, Obolensk, Moscow Region, 142279 Russia
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22
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Liu W, Nestorovich EM. Anthrax toxin channel: What we know based on over 30 years of research. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183715. [PMID: 34332985 DOI: 10.1016/j.bbamem.2021.183715] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 03/20/2021] [Revised: 07/21/2021] [Accepted: 07/24/2021] [Indexed: 10/20/2022]
Abstract
Protective antigen channel is the central component of the deadly anthrax exotoxin responsible for binding and delivery of the toxin's enzymatic lethal and edema factor components into the cytosol. The channel, which is more than three times longer than the lipid bilayer membrane thickness and has a 6-Å limiting diameter, is believed to provide a sophisticated unfoldase and translocase machinery for the foreign protein transport into the host cell cytosol. The tripartite toxin can be reengineered, one component at a time or collectively, to adapt it for the targeted cancer therapeutic treatments. In this review, we focus on the biophysical studies of the protective antigen channel-forming activity, small ion transport properties, enzymatic factor translocation, and blockage comparing it with the related clostridial binary toxin channels. We address issues linked to the anthrax toxin channel structural dynamics and lipid dependence, which are yet to become generally recognized as parts of the toxin translocation machinery.
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Affiliation(s)
- Wenxing Liu
- Department of Biology, The Catholic University of America, 620 Michigan Ave, Washington, DC 20064, USA
| | - Ekaterina M Nestorovich
- Department of Biology, The Catholic University of America, 620 Michigan Ave, Washington, DC 20064, USA.
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23
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Essen LO, Vogt MS, Mösch HU. Diversity of GPI-anchored fungal adhesins. Biol Chem 2021; 401:1389-1405. [PMID: 33035180 DOI: 10.1515/hsz-2020-0199] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 09/21/2020] [Indexed: 12/28/2022]
Abstract
Selective adhesion of fungal cells to one another and to foreign surfaces is fundamental for the development of multicellular growth forms and the successful colonization of substrates and host organisms. Accordingly, fungi possess diverse cell wall-associated adhesins, mostly large glycoproteins, which present N-terminal adhesion domains at the cell surface for ligand recognition and binding. In order to function as robust adhesins, these glycoproteins must be covalently linkedto the cell wall via C-terminal glycosylphosphatidylinositol (GPI) anchors by transglycosylation. In this review, we summarize the current knowledge on the structural and functional diversity of so far characterized protein families of adhesion domains and set it into a broad context by an in-depth bioinformatics analysis using sequence similarity networks. In addition, we discuss possible mechanisms for the membrane-to-cell wall transfer of fungal adhesins by membrane-anchored Dfg5 transglycosidases.
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Affiliation(s)
- Lars-Oliver Essen
- Department of Biochemistry, Faculty of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Straße 4, D-35043Marburg, Germany.,Center for Synthetic Microbiology, Philipps-Universität Marburg, Karl-von-Frisch-Str. 6, D-35043Marburg, Germany
| | - Marian Samuel Vogt
- Department of Biochemistry, Faculty of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Straße 4, D-35043Marburg, Germany
| | - Hans-Ulrich Mösch
- Department of Genetics, Philipps-Universität Marburg, Karl-von-Frisch-Str. 8, D-35043Marburg, Germany.,Center for Synthetic Microbiology, Philipps-Universität Marburg, Karl-von-Frisch-Str. 6, D-35043Marburg, Germany
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24
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Yamini G, Kanchi S, Kalu N, Momben Abolfath S, Leppla SH, Ayappa KG, Maiti PK, Nestorovich EM. Hydrophobic Gating and 1/ f Noise of the Anthrax Toxin Channel. J Phys Chem B 2021; 125:5466-5478. [PMID: 34015215 DOI: 10.1021/acs.jpcb.0c10490] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
"Pink" or 1/f noise is a natural phenomenon omnipresent in physics, economics, astrophysics, biology, and even music and languages. In electrophysiology, the stochastic activity of a number of biological ion channels and artificial nanopores could be characterized by current noise with a 1/f power spectral density. In the anthrax toxin channel (PA63), it appears as fast voltage-independent current interruptions between conducting and nonconducting states. This behavior hampers potential development of PA63 as an ion-channel biosensor. On the bright side, the PA63 flickering represents a mesmerizing phenomenon to investigate. Notably, similar 1/f fluctuations are observed in the channel-forming components of clostridial binary C2 and iota toxins, which share functional and structural similarities with the anthrax toxin channel. Similar to PA63, they are evolved to translocate the enzymatic components of the toxins into the cytosol. Here, using high-resolution single-channel lipid bilayer experiments and all-atom molecular dynamic simulations, we suggest that the 1/f noise in PA63 occurs as a result of "hydrophobic gating" at the ϕ-clamp region, the phenomenon earlier observed in several water-filled channels "fastened" inside by the hydrophobic belts. The ϕ-clamp is a narrow "hydrophobic ring" in the PA63 lumen formed by seven or eight phenylalanine residues at position 427, conserved in the C2 and iota toxin channels, which catalyzes protein translocation. Notably, the 1/f noise remains undetected in the F427A PA63 mutant. This finding can elucidate the functional purpose of 1/f noise and its possible role in the transport of the enzymatic components of binary toxins.
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Affiliation(s)
- Goli Yamini
- Department of Biology, The Catholic University of America, 620 Michigan Avenue, Washington D.C., 20064, United States
| | - Subbarao Kanchi
- Department of Chemical Engineering, Indian Institute of Science, Bengaluru 560012, India.,Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bengaluru 560012, India
| | - Nnanya Kalu
- Department of Biology, The Catholic University of America, 620 Michigan Avenue, Washington D.C., 20064, United States
| | - Sanaz Momben Abolfath
- Department of Biology, The Catholic University of America, 620 Michigan Avenue, Washington D.C., 20064, United States
| | - Stephen H Leppla
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - K Ganapathy Ayappa
- Department of Chemical Engineering, Indian Institute of Science, Bengaluru 560012, India
| | - Prabal K Maiti
- Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bengaluru 560012, India
| | - Ekaterina M Nestorovich
- Department of Biology, The Catholic University of America, 620 Michigan Avenue, Washington D.C., 20064, United States
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Nath P, Goyal A. Structure and dynamics analysis of multi-domain putative β-1,4-glucosidase of family 3 glycoside hydrolase (PsGH3) from Pseudopedobacter saltans. J Mol Model 2021; 27:106. [PMID: 33694107 PMCID: PMC7945971 DOI: 10.1007/s00894-021-04721-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 03/01/2021] [Indexed: 11/30/2022]
Abstract
Structure and conformational behaviour of a putative β-1,4-glucosidase of glycoside hydrolase family 3 (PsGH3) from Pseudopedobacter saltans was predicted by using in-silico tools. PsGH3 modeled structure constructed using Phyre2 displayed multidomain architecture comprising an N-terminal (β/α)8-fold domain followed by (α/β)6-sandwich domain, PA14 domain, and a C-terminal domain resembling an immunoglobulin fold. Ramachandran plot displayed 99.3% of amino acids in the allowed region and 0.7% residues in the disallowed region. Multiple sequence alignment (MSA) and structure superposition of PsGH3 with other homologues from GH3 family revealed the conserved residues, Asp274 and Glu624 present in loops LA and LB, respectively originating from N-terminal domain act as catalytic residues. The volume and area calculated for PsGH3 displayed a deep active-site conformation comparable with its homologues, β-1,4-glucosidases (GH3) of Kluyveromyces marxianus and Streptomyces venezuelae. Molecular dynamic (MD) simulation of PsGH3 structure for 80 ns suggested stable and compact structure. Molecular docking studies revealed deeper active site conformation of PsGH3 that could house larger cellooligosaccharides up to 7° of polymerization (DP7). The amino acid residues, Ala86, Leu88, Cys275, Pro483, Phe493, Asn417, Asn491, Pro492, and Leu495 created a binding pocket near the catalytic cleft, crucial for ligand binding. MD simulation of PsGH3 in the presence of cellooligosaccharides, viz., cellobiose and celloheptaose showed stability in terms of RMSD, Rg, and SASA values till 80 ns. The calculation of average number of hydrogen bond (H-bond), interaction energy, and binding free energy confirmed the stronger binding affinity of the larger cellooligosaccharides such as celloheptaose in the binding cavity of PsGH3.
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Affiliation(s)
- Priyanka Nath
- Carbohydrate Enzyme Biotechnology Laboratory, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, Assam, 781039, India
| | - Arun Goyal
- Carbohydrate Enzyme Biotechnology Laboratory, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, Assam, 781039, India.
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Landenberger M, Nieland J, Roeder M, Nørgaard K, Papatheodorou P, Ernst K, Barth H. The cytotoxic effect of Clostridioides difficile pore-forming toxin CDTb. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183603. [PMID: 33689753 DOI: 10.1016/j.bbamem.2021.183603] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 02/26/2021] [Accepted: 03/03/2021] [Indexed: 01/05/2023]
Abstract
Clostridioides (C.) difficile is clinically highly relevant and produces several AB-type protein toxins, which are the causative agents for C. difficile-associated diarrhea and pseudomembranous colitis. Treatment with antibiotics can lead to C. difficile overgrowth in the gut of patients due to the disturbed microbiota. C. difficile releases large Rho/Ras-GTPase glucosylating toxins TcdA and TcdB, which are considered as the major virulence factors for C. difficile-associated diseases. In addition to TcdA and TcdB, C. difficile strains isolated from severe cases of colitis produce a third toxin called CDT. CDT is a member of the family of clostridial binary actin ADP-ribosylating toxins and consists of two separate protein components. The B-component, CDTb, binds to the receptor and forms a complex with and facilitates transport and translocation of the enzymatically active A-component, CDTa, into the cytosol of target cells by forming trans-membrane pores through which CDTa translocates. In the cytosol, CDTa ADP-ribosylates G-actin causing depolymerization of the actin cytoskeleton and, eventually, cell death. In the present study, we report that CDTb exhibits a cytotoxic effect in the absence of CDTa. We show that CDTb causes cell rounding and impairs cell viability and the epithelial integrity of CaCo-2 monolayers in the absence of CDTa. CDTb-induced cell rounding depended on the presence of LSR, the specific cellular receptor of CDT. The isolated receptor-binding domain of CDTb was not sufficient to cause cell rounding. CDTb-induced cell rounding was inhibited by enzymatically inactive CDTa or a pore-blocker, implying that CDTb pores in cytoplasmic membranes contribute to cytotoxicity.
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Affiliation(s)
- Marc Landenberger
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, Ulm, Germany
| | - Julian Nieland
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, Ulm, Germany
| | - Maurice Roeder
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, Ulm, Germany
| | - Katharina Nørgaard
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, Ulm, Germany
| | | | - Katharina Ernst
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, Ulm, Germany.
| | - Holger Barth
- Institute of Pharmacology and Toxicology, Ulm University Medical Center, Ulm, Germany
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Abstract
Anthrax toxin is a major virulence factor of Bacillus anthracis, a Gram-positive bacterium which can form highly stable spores that are the causative agents of the disease, anthrax. While chiefly a disease of livestock, spores can be "weaponized" as a bio-terrorist agent, and can be deadly if not recognized and treated early with antibiotics. The intracellular pathways affected by the enzymes are broadly understood and are not discussed here. This chapter focuses on what is known about the assembly of secreted toxins on the host cell surface and how the toxin is delivered into the cytosol. The central component is the "Protective Antigen", which self-oligomerizes and forms complexes with its pay-load, either Lethal Factor or Edema Factor. It binds a host receptor, CMG2, or a close relative, triggering receptor-mediated endocytosis, and forms a remarkably elegant yet powerful machine that delivers toxic enzymes into the cytosol, powered only by the pH gradient across the membrane. We now have atomic structures of most of the starting, intermediate and final assemblies in the infectious process. Together with a major body of biophysical, mutational and biochemical work, these studies reveal a remarkable story of both how toxin assembly is choreographed in time and space.
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Pore-forming proteins: From defense factors to endogenous executors of cell death. Chem Phys Lipids 2020; 234:105026. [PMID: 33309552 DOI: 10.1016/j.chemphyslip.2020.105026] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 12/07/2020] [Accepted: 12/07/2020] [Indexed: 02/06/2023]
Abstract
Pore-forming proteins (PFPs) and small antimicrobial peptides (AMPs) represent a large family of molecules with the common ability to punch holes in cell membranes to alter their permeability. They play a fundamental role as infectious bacteria's defensive tools against host's immune system and as executors of endogenous machineries of regulated cell death in eukaryotic cells. Despite being highly divergent in primary sequence and 3D structure, specific folds of pore-forming domains have been conserved. In fact, pore formation is considered an ancient mechanism that takes place through a general multistep process involving: membrane partitioning and insertion, oligomerization and pore formation. However, different PFPs and AMPs assemble and form pores following different mechanisms that could end up either in the formation of protein-lined or protein-lipid pores. In this review, we analyze the current findings in the mechanism of action of different PFPs and AMPs that support a wide role of membrane pore formation in nature. We also provide the newest insights into the development of state-of-art techniques that have facilitated the characterization of membrane pores. To understand the physiological role of these peptides/proteins or develop clinical applications, it is essential to uncover the molecular mechanism of how they perforate membranes.
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Ni X, Jiang J. Cryo-EM Uncovers Atomic Details for Loading Cell-Killing Enzymes to the Anthrax Toxin Pretranslocation Complex. Structure 2020; 28:871-873. [PMID: 32755568 DOI: 10.1016/j.str.2020.07.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In this issue of Structure, Zhou et al. report the structures of full-length lethal and edema factors, the cytotoxic components of the deadly anthrax toxin, in complex with the toxin's cell binding and delivery module, the protective antigen prechannel, providing an atomic description for the toxin recruitment prior to translocation.
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Affiliation(s)
- Xiaodan Ni
- Laboratory of Membrane Proteins and Structural Biology, Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jiansen Jiang
- Laboratory of Membrane Proteins and Structural Biology, Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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30
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Loftis AR, Santos MS, Truex NL, Biancucci M, Satchell KJF, Pentelute BL. Anthrax Protective Antigen Retargeted with Single-Chain Variable Fragments Delivers Enzymes to Pancreatic Cancer Cells. Chembiochem 2020; 21:2772-2776. [PMID: 32369652 PMCID: PMC7541672 DOI: 10.1002/cbic.202000201] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 05/01/2020] [Indexed: 12/15/2022]
Abstract
The nontoxic, anthrax protective antigen/lethal factor N-terminal domain (PA/LFN ) complex is an effective platform for translocating proteins into the cytosol of cells. Mutant PA (mPA) was recently fused to epidermal growth factor (EGF) to retarget delivery of LFN to cells bearing EGF receptors (EGFR), but the requirement for a known cognate ligand limits the applicability of this approach. Here, we render practical protective antigen retargeting to a variety of receptors with mPA single-chain variable fragment (scFv) fusion constructs. Our design enables the targeting of two pancreatic cancer-relevant receptors, EGFR and carcinoembryonic antigen. We demonstrate that fusion to scFvs does not disturb the basic functions of mPA. Moreover, mPA-scFv fusions enable cell-specific delivery of diphtheria toxin catalytic domain and Ras/Rap1-specific endopeptidase to pancreatic cancer cells. Importantly, mPA-scFv fusion-based treatments display potent cell-specific toxicity in vitro, opening fundamentally new routes toward engineered immunotoxins and providing a potential solution to the challenge of targeted protein delivery to the cytosol of cancer cells.
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Affiliation(s)
- Alexander R Loftis
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - Michael S Santos
- Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - Nicholas L Truex
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - Marco Biancucci
- Department of Microbiology-Immunology Feinberg School of Medicine, Northwestern University, 420 E Superior Street, Chicago, IL 60611, USA
| | - Karla J F Satchell
- Department of Microbiology-Immunology Feinberg School of Medicine, Northwestern University, 420 E Superior Street, Chicago, IL 60611, USA
| | - Bradley L Pentelute
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
- The Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, 500 Main Street, Cambridge, MA 02142, USA
- Center for Environmental Health Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
- Broad Institute of MIT and Harvard, 415 Main Street, Cambridge, MA 02142, USA
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Alameh S, Bartolo G, O’Brien S, Henderson EA, Gonzalez LO, Hartmann S, Klimko CP, Shoe JL, Cote CK, Grill LK, Levitin A, Martchenko Shilman M. Anthrax toxin component, Protective Antigen, protects insects from bacterial infections. PLoS Pathog 2020; 16:e1008836. [PMID: 32866212 PMCID: PMC7458312 DOI: 10.1371/journal.ppat.1008836] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 07/24/2020] [Indexed: 01/23/2023] Open
Abstract
Anthrax is a major zoonotic disease of wildlife, and in places like West Africa, it can be caused by Bacillus anthracis in arid nonsylvatic savannahs, and by B. cereus biovar anthracis (Bcbva) in sylvatic rainforests. Bcbva-caused anthrax has been implicated in as much as 38% of mortality in rainforest ecosystems, where insects can enhance the transmission of anthrax-causing bacteria. While anthrax is well-characterized in mammals, its transmission by insects points to an unidentified anthrax-resistance mechanism in its vectors. In mammals, a secreted anthrax toxin component, 83 kDa Protective Antigen (PA83), binds to cell-surface receptors and is cleaved by furin into an evolutionary-conserved PA20 and a pore-forming PA63 subunits. We show that PA20 increases the resistance of Drosophila flies and Culex mosquitoes to bacterial challenges, without directly affecting the bacterial growth. We further show that the PA83 loop known to be cleaved by furin to release PA20 from PA63 is, in part, responsible for the PA20-mediated protection. We found that PA20 binds directly to the Toll activating peptidoglycan-recognition protein-SA (PGRP-SA) and that the Toll/NF-κB pathway is necessary for the PA20-mediated protection of infected flies. This effect of PA20 on innate immunity may also exist in mammals: we show that PA20 binds to human PGRP-SA ortholog. Moreover, the constitutive activity of Imd/NF-κB pathway in MAPKK Dsor1 mutant flies is sufficient to confer the protection from bacterial infections in a manner that is independent of PA20 treatment. Lastly, Clostridium septicum alpha toxin protects flies from anthrax-causing bacteria, showing that other pathogens may help insects resist anthrax. The mechanism of anthrax resistance in insects has direct implications on insect-mediated anthrax transmission for wildlife management, and with potential for applications, such as reducing the sensitivity of pollinating insects to bacterial pathogens.
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Affiliation(s)
- Saleem Alameh
- Henry E. Riggs School of Applied Life Sciences, Keck Graduate Institute, Claremont, California, United States of America
| | - Gloria Bartolo
- Henry E. Riggs School of Applied Life Sciences, Keck Graduate Institute, Claremont, California, United States of America
| | - Summer O’Brien
- Henry E. Riggs School of Applied Life Sciences, Keck Graduate Institute, Claremont, California, United States of America
| | - Elizabeth A. Henderson
- Henry E. Riggs School of Applied Life Sciences, Keck Graduate Institute, Claremont, California, United States of America
| | - Leandra O. Gonzalez
- Henry E. Riggs School of Applied Life Sciences, Keck Graduate Institute, Claremont, California, United States of America
| | - Stella Hartmann
- Henry E. Riggs School of Applied Life Sciences, Keck Graduate Institute, Claremont, California, United States of America
| | - Christopher P. Klimko
- Bacteriology Division, US Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, Maryland, United States of America
| | - Jennifer L. Shoe
- Bacteriology Division, US Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, Maryland, United States of America
| | - Christopher K. Cote
- Bacteriology Division, US Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, Maryland, United States of America
| | - Laurence K. Grill
- Henry E. Riggs School of Applied Life Sciences, Keck Graduate Institute, Claremont, California, United States of America
| | - Anastasia Levitin
- Henry E. Riggs School of Applied Life Sciences, Keck Graduate Institute, Claremont, California, United States of America
- * E-mail: (AL); (MMS)
| | - Mikhail Martchenko Shilman
- Henry E. Riggs School of Applied Life Sciences, Keck Graduate Institute, Claremont, California, United States of America
- * E-mail: (AL); (MMS)
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Cryo-EM structure of the fully-loaded asymmetric anthrax lethal toxin in its heptameric pre-pore state. PLoS Pathog 2020; 16:e1008530. [PMID: 32810181 PMCID: PMC7462287 DOI: 10.1371/journal.ppat.1008530] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2020] [Revised: 09/01/2020] [Accepted: 06/27/2020] [Indexed: 12/20/2022] Open
Abstract
Anthrax toxin is the major virulence factor secreted by Bacillus anthracis, causing high mortality in humans and other mammals. It consists of a membrane translocase, known as protective antigen (PA), that catalyzes the unfolding of its cytotoxic substrates lethal factor (LF) and edema factor (EF), followed by translocation into the host cell. Substrate recruitment to the heptameric PA pre-pore and subsequent translocation, however, are not well understood. Here, we report three high-resolution cryo-EM structures of the fully-loaded anthrax lethal toxin in its heptameric pre-pore state, which differ in the position and conformation of LFs. The structures reveal that three LFs interact with the heptameric PA and upon binding change their conformation to form a continuous chain of head-to-tail interactions. As a result of the underlying symmetry mismatch, one LF binding site in PA remains unoccupied. Whereas one LF directly interacts with a part of PA called α-clamp, the others do not interact with this region, indicating an intermediate state between toxin assembly and translocation. Interestingly, the interaction of the N-terminal domain with the α-clamp correlates with a higher flexibility in the C-terminal domain of the protein. Based on our data, we propose a model for toxin assembly, in which the relative position of the N-terminal α-helices in the three LFs determines which factor is translocated first.
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33
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Roonie A, Majumder S, Kingston JJ, Parida M. Molecular characterization of B. anthracis isolates from the anthrax outbreak among cattle in Karnataka, India. BMC Microbiol 2020; 20:232. [PMID: 32736522 PMCID: PMC7394690 DOI: 10.1186/s12866-020-01917-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Accepted: 07/21/2020] [Indexed: 12/02/2022] Open
Abstract
Background Anthrax, a zoonotic disease is caused by the Gram positive bacterium Bacillus anthracis. During January 2013, an anthrax outbreak among cattle was reported in Gundlupet Taluk, neighboring Bandipur National Park and tiger reserve, India. The present study aims at the molecular identification and characterization of 12 B. anthracis isolates from this outbreak by 16S rRNA gene sequencing, screening B. anthracis specific prophages and chromosomal markers, protective antigen (pag) gene and canonical single nucleotide polymorphism (canSNP) analysis to subtype the isolates into one of the twelve globally identified clonal sub-lineages of B. anthracis. Results These isolates had identical 16S rDNA nucleotide sequences with B. anthracis specific dual peaks showing mixed base pair R (G/A) at position 1139 with visual inspection while the automated basecaller software indicated a G. Alternatively the nucleotide A at 1146 position was indicative of the 16S rDNA type 7. Multiple sequence alignment with additional 170 (16S rDNA) sequences of B. cereus sensu lato group from GenBank database revealed 28 new 16S types in addition to eleven 16S types reported earlier. The twelve B. anthracis isolates were found to harbor the four B. anthracis specific prophages (lambdaBa01, lambdaBa02, lambdaBa03, and lambdaBa04) along with its four specific loci markers (dhp 61.183, dhp 77.002, dhp 73.019, and dhp 73.017). The pag gene sequencing identified the isolates as protective antigen (PA) genotype I with phenylalanine-proline-alanine phenotype (FPA phenotype). However, sequence clustering with additional 34 pag sequences from GenBank revealed two additional missense mutations at nucleotide positions 196 bp and 869 bp of the 2294 bp pag sequence among the 5 B. cereus strains with pXO1 like plasmids. The canSNP analysis showed that the isolates belong to A.Br.Aust94 sub-lineage that is distributed geographically in countries of Asia, Africa, Europe and Australia. Conclusions The analysis of 16S rDNA sequences reiterated the earlier findings that visual inspection of electropherogram for position 1139 having nucleotide R could be used for B. anthracis identification and not the consensus sequence from base caller. The canSNP results indicated that the anthrax outbreak among cattle was caused by B. anthracis of A.Br.Aust94 sub-lineage.
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Affiliation(s)
- Akanxa Roonie
- Microbiology Division, Defence Food Research Laboratory, Siddartha Nagar, Mysore, Karnataka, 570011, India
| | - Saugata Majumder
- Microbiology Division, Defence Food Research Laboratory, Siddartha Nagar, Mysore, Karnataka, 570011, India
| | - Joseph J Kingston
- Microbiology Division, Defence Food Research Laboratory, Siddartha Nagar, Mysore, Karnataka, 570011, India.
| | - Manmohan Parida
- Microbiology Division, Defence Food Research Laboratory, Siddartha Nagar, Mysore, Karnataka, 570011, India
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34
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Hoffmann D, Diderrich R, Reithofer V, Friederichs S, Kock M, Essen LO, Mösch HU. Functional reprogramming of Candida glabrata epithelial adhesins: the role of conserved and variable structural motifs in ligand binding. J Biol Chem 2020; 295:12512-12524. [PMID: 32669365 DOI: 10.1074/jbc.ra120.013968] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 07/10/2020] [Indexed: 12/11/2022] Open
Abstract
For host-cell interaction, the human fungal pathogen Candida glabrata harbors a large family of more than 20 cell wall-attached epithelial adhesins (Epas). Epa family members are lectins with binding pockets containing several conserved and variable structural hot spots, which were implicated in mediating functional diversity. In this study, we have performed an elaborate structure-based mutational analysis of numerous Epa paralogs to generally determine the role of diverse structural hot spots in conferring host cell binding and ligand binding specificity. Our study reveals that several conserved structural motifs contribute to efficient host cell binding. Moreover, our directed motif exchange experiments reveal that the variable loop CBL2 is key for programming ligand binding specificity, albeit with limited predictability. In contrast, we find that the variable loop L1 affects host cell binding without significantly influencing the specificity of ligand binding. Our data strongly suggest that variation of numerous structural hot spots in the ligand binding pocket of Epa proteins is a main driver of their functional diversification and evolution.
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Affiliation(s)
- Daniel Hoffmann
- Department of Genetics, Philipps-Universität, Marburg, Germany
| | - Rike Diderrich
- Department of Genetics, Philipps-Universität, Marburg, Germany
| | | | | | - Michael Kock
- Department of Biochemistry, Philipps-Universität, Marburg, Germany
| | - Lars-Oliver Essen
- Department of Biochemistry, Philipps-Universität, Marburg, Germany .,Center for Synthetic Microbiology, Philipps-Universität, Marburg, Germany
| | - Hans-Ulrich Mösch
- Department of Genetics, Philipps-Universität, Marburg, Germany .,Center for Synthetic Microbiology, Philipps-Universität, Marburg, Germany
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Zhou K, Liu S, Hardenbrook NJ, Cui Y, Krantz BA, Zhou ZH. Atomic Structures of Anthrax Prechannel Bound with Full-Length Lethal and Edema Factors. Structure 2020; 28:879-887.e3. [PMID: 32521227 DOI: 10.1016/j.str.2020.05.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Revised: 04/09/2020] [Accepted: 05/18/2020] [Indexed: 12/15/2022]
Abstract
Pathogenesis of anthrax disease involves two cytotoxic enzymes-edema factor (EF) and lethal factor (LF)-which are individually recruited by the protective antigen heptamer (PA7) or octamer (PA8) prechannel and subsequently translocated across channels formed on the endosomal membrane upon exposure to low pH. Here, we report the atomic structures of PA8 prechannel-bound full-length EF and LF. In this pretranslocation state, the N-terminal segment of both factors refolds into an α helix engaged in the α clamp of the prechannel. Recruitment to the PA prechannel exposes an originally buried β strand of both toxins and enables domain organization of EF. Many interactions occur on domain interfaces in both PA prechannel-bound EF and LF, leading to toxin compaction prior to translocation. Our results provide key insights into the molecular mechanisms of translocation-coupled protein unfolding and translocation.
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Affiliation(s)
- Kang Zhou
- California NanoSystems Institute, University of California, Los Angeles, CA 90095, USA
| | - Shiheng Liu
- California NanoSystems Institute, University of California, Los Angeles, CA 90095, USA; Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, CA 90095, USA
| | - Nathan J Hardenbrook
- Department of Microbial Pathogenesis, University of Maryland, Baltimore, Baltimore, MD 21201, USA
| | - Yanxiang Cui
- California NanoSystems Institute, University of California, Los Angeles, CA 90095, USA
| | - Bryan A Krantz
- Department of Microbial Pathogenesis, University of Maryland, Baltimore, Baltimore, MD 21201, USA.
| | - Z Hong Zhou
- California NanoSystems Institute, University of California, Los Angeles, CA 90095, USA; Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, CA 90095, USA.
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36
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Yeast Flocculin: Methods for Quantitative Analysis of Flocculation in Yeast Cells. Methods Mol Biol 2020. [PMID: 32306350 DOI: 10.1007/978-1-0716-0430-4_42] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Flocculation, the clump forming property of yeast, has long been appreciated in breweries and utilized as an off-cost method to enable the reuse of yeast cells. Members of the flocculin protein family were identified as the adherent proteins on the cell surface responsible for flocculation, and their properties have been investigated. Crystal structures of the adhesion domain of flocculins revealed their unique mode of ligand binding where a calcium ion is located in the middle of the interface between flocculin and the interacting sugar. Here we describe the most commonly used flocculation assay. The method is simple and easy, yet it is the most direct and reliable assay to evaluate the flocculation cellular phenotype.
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37
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Yamada T, Yoshida T, Kawamoto A, Mitsuoka K, Iwasaki K, Tsuge H. Cryo-EM structures reveal translocational unfolding in the clostridial binary iota toxin complex. Nat Struct Mol Biol 2020; 27:288-296. [PMID: 32123390 DOI: 10.1038/s41594-020-0388-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 01/17/2020] [Indexed: 11/09/2022]
Abstract
The iota toxin produced by Clostridium perfringens type E is a binary toxin comprising two independent polypeptides: Ia, an ADP-ribosyltransferase, and Ib, which is involved in cell binding and translocation of Ia across the cell membrane. Here we report cryo-EM structures of the translocation channel Ib-pore and its complex with Ia. The high-resolution Ib-pore structure demonstrates a similar structural framework to that of the catalytic ϕ-clamp of the anthrax protective antigen pore. However, the Ia-bound Ib-pore structure shows a unique binding mode of Ia: one Ia binds to the Ib-pore, and the Ia amino-terminal domain forms multiple weak interactions with two additional Ib-pore constriction sites. Furthermore, Ib-binding induces tilting and partial unfolding of the Ia N-terminal α-helix, permitting its extension to the ϕ-clamp gate. This new mechanism of N-terminal unfolding is crucial for protein translocation.
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Affiliation(s)
- Tomohito Yamada
- Faculty of Life Sciences, Kyoto Sangyo University, Kamigamo-motoyama, Kita-ku, Kyoto, Japan
| | - Toru Yoshida
- Faculty of Life Sciences, Kyoto Sangyo University, Kamigamo-motoyama, Kita-ku, Kyoto, Japan.,Institute for Protein Dynamics, Kyoto Sangyo University, Kamigamo-motoyama, Kita-ku, Kyoto, Japan
| | - Akihiro Kawamoto
- Institute for Protein Research, Osaka University, Suita, Osaka, Japan
| | - Kaoru Mitsuoka
- Research Center for Ultra-High Voltage Electron Microscopy, Osaka University, Ibaraki, Osaka, Japan
| | - Kenji Iwasaki
- Institute for Protein Research, Osaka University, Suita, Osaka, Japan.,Life Science Center for Survival Dynamics, Tsukuba Advanced Research Alliance (TARA), University of Tsukuba, Tsukuba, Japan
| | - Hideaki Tsuge
- Faculty of Life Sciences, Kyoto Sangyo University, Kamigamo-motoyama, Kita-ku, Kyoto, Japan. .,Institute for Protein Dynamics, Kyoto Sangyo University, Kamigamo-motoyama, Kita-ku, Kyoto, Japan. .,Center for Molecular Research in Infectious Diseases, Kyoto Sangyo University, Kamigamo-motoyama, Kita-ku, Kyoto, Japan.
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38
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Xu X, Godoy-Ruiz R, Adipietro KA, Peralta C, Ben-Hail D, Varney KM, Cook ME, Roth BM, Wilder PT, Cleveland T, Grishaev A, Neu HM, Michel SLJ, Yu W, Beckett D, Rustandi RR, Lancaster C, Loughney JW, Kristopeit A, Christanti S, Olson JW, MacKerell AD, Georges AD, Pozharski E, Weber DJ. Structure of the cell-binding component of the Clostridium difficile binary toxin reveals a di-heptamer macromolecular assembly. Proc Natl Acad Sci U S A 2020; 117:1049-1058. [PMID: 31896582 PMCID: PMC6969506 DOI: 10.1073/pnas.1919490117] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Targeting Clostridium difficile infection is challenging because treatment options are limited, and high recurrence rates are common. One reason for this is that hypervirulent C. difficile strains often have a binary toxin termed the C. difficile toxin, in addition to the enterotoxins TsdA and TsdB. The C. difficile toxin has an enzymatic component, termed CDTa, and a pore-forming or delivery subunit termed CDTb. CDTb was characterized here using a combination of single-particle cryoelectron microscopy, X-ray crystallography, NMR, and other biophysical methods. In the absence of CDTa, 2 di-heptamer structures for activated CDTb (1.0 MDa) were solved at atomic resolution, including a symmetric (SymCDTb; 3.14 Å) and an asymmetric form (AsymCDTb; 2.84 Å). Roles played by 2 receptor-binding domains of activated CDTb were of particular interest since the receptor-binding domain 1 lacks sequence homology to any other known toxin, and the receptor-binding domain 2 is completely absent in other well-studied heptameric toxins (i.e., anthrax). For AsymCDTb, a Ca2+ binding site was discovered in the first receptor-binding domain that is important for its stability, and the second receptor-binding domain was found to be critical for host cell toxicity and the di-heptamer fold for both forms of activated CDTb. Together, these studies represent a starting point for developing structure-based drug-design strategies to target the most severe strains of C. difficile.
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Affiliation(s)
- Xingjian Xu
- City University of New York Advanced Science Research Center, City University of New York, New York, NY 10017
- PhD Program in Biochemistry, The Graduate Center, City University of New York, New York, NY 10017
| | - Raquel Godoy-Ruiz
- Department of Biochemistry & Molecular Biology, University of Maryland School of Medicine, University of Maryland, Baltimore, MD 21201
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD 20850
- The Center for Biomolecular Therapeutics, The University of Maryland School of Medicine, University of Maryland, Baltimore, MD 21201
| | - Kaylin A Adipietro
- Department of Biochemistry & Molecular Biology, University of Maryland School of Medicine, University of Maryland, Baltimore, MD 21201
- The Center for Biomolecular Therapeutics, The University of Maryland School of Medicine, University of Maryland, Baltimore, MD 21201
| | - Christopher Peralta
- City University of New York Advanced Science Research Center, City University of New York, New York, NY 10017
| | - Danya Ben-Hail
- City University of New York Advanced Science Research Center, City University of New York, New York, NY 10017
| | - Kristen M Varney
- Department of Biochemistry & Molecular Biology, University of Maryland School of Medicine, University of Maryland, Baltimore, MD 21201
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD 20850
- The Center for Biomolecular Therapeutics, The University of Maryland School of Medicine, University of Maryland, Baltimore, MD 21201
| | - Mary E Cook
- Department of Biochemistry & Molecular Biology, University of Maryland School of Medicine, University of Maryland, Baltimore, MD 21201
- The Center for Biomolecular Therapeutics, The University of Maryland School of Medicine, University of Maryland, Baltimore, MD 21201
| | - Braden M Roth
- Department of Biochemistry & Molecular Biology, University of Maryland School of Medicine, University of Maryland, Baltimore, MD 21201
| | - Paul T Wilder
- Department of Biochemistry & Molecular Biology, University of Maryland School of Medicine, University of Maryland, Baltimore, MD 21201
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD 20850
- The Center for Biomolecular Therapeutics, The University of Maryland School of Medicine, University of Maryland, Baltimore, MD 21201
| | | | | | - Heather M Neu
- University of Maryland School of Pharmacy, University of Maryland, Baltimore, MD 21201
| | - Sarah L J Michel
- University of Maryland School of Pharmacy, University of Maryland, Baltimore, MD 21201
| | - Wenbo Yu
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD 20850
- The Center for Biomolecular Therapeutics, The University of Maryland School of Medicine, University of Maryland, Baltimore, MD 21201
- University of Maryland School of Pharmacy, University of Maryland, Baltimore, MD 21201
| | - Dorothy Beckett
- Department of Chemistry & Biochemistry, University of Maryland, College Park, MD 20742
| | | | | | | | | | | | | | - Alexander D MacKerell
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD 20850
- The Center for Biomolecular Therapeutics, The University of Maryland School of Medicine, University of Maryland, Baltimore, MD 21201
- University of Maryland School of Pharmacy, University of Maryland, Baltimore, MD 21201
| | - Amedee des Georges
- City University of New York Advanced Science Research Center, City University of New York, New York, NY 10017;
- PhD Program in Biochemistry, The Graduate Center, City University of New York, New York, NY 10017
- PhD Program in Chemistry, The Graduate Center, City University of New York, New York, NY 10017
- Department of Chemistry & Biochemistry, City College of New York, New York, NY 10031
| | - Edwin Pozharski
- Department of Biochemistry & Molecular Biology, University of Maryland School of Medicine, University of Maryland, Baltimore, MD 21201;
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD 20850
- The Center for Biomolecular Therapeutics, The University of Maryland School of Medicine, University of Maryland, Baltimore, MD 21201
| | - David J Weber
- Department of Biochemistry & Molecular Biology, University of Maryland School of Medicine, University of Maryland, Baltimore, MD 21201;
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD 20850
- The Center for Biomolecular Therapeutics, The University of Maryland School of Medicine, University of Maryland, Baltimore, MD 21201
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39
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Luong P, Li Q, Chen PF, Wrighton PJ, Chang D, Dwyer S, Bayer MT, Snapper SB, Hansen SH, Thiagarajah JR, Goessling W, Lencer WI. A quantitative single-cell assay for retrograde membrane traffic enables rapid detection of defects in cellular organization. Mol Biol Cell 2019; 31:511-519. [PMID: 31774722 PMCID: PMC7202069 DOI: 10.1091/mbc.e19-07-0375] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Retrograde membrane trafficking from plasma membrane to Golgi and endoplasmic reticulum typifies one of the key sorting steps emerging from the early endosome that affects cell surface and intracellular protein dynamics underlying cell function. While some cell surface proteins and lipids are known to sort retrograde, there are few effective methods to quantitatively measure the extent or kinetics of these events. Here we took advantage of the well-known retrograde trafficking of cholera toxin and newly defined split fluorescent protein technology to develop a quantitative, sensitive, and effectively real-time single-cell flow cytometry assay for retrograde membrane transport. The approach can be applied in high throughput to elucidate the underlying biology of membrane traffic and how endosomes adapt to the physiologic needs of different cell types and cell states.
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Affiliation(s)
- Phi Luong
- Department of Pediatrics, Harvard Medical School, and.,Division of Gastroenterology, Boston Children's Hospital, Boston, MA 02115
| | - Qian Li
- Department of Pediatrics, Harvard Medical School, and.,Division of Gastroenterology, Boston Children's Hospital, Boston, MA 02115.,Shanghai Children's Hospital, Shanghai Jiaotong University, Shanghai 200000, China
| | - Pin-Fang Chen
- F.M. Kirby Neurobiology Center, Translational Neuroscience Center, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115
| | - Paul J Wrighton
- Division of Genetics, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115
| | - Denis Chang
- Department of Pediatrics, Harvard Medical School, and.,Division of Gastroenterology, Boston Children's Hospital, Boston, MA 02115
| | - Sean Dwyer
- F.M. Kirby Neurobiology Center, Translational Neuroscience Center, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115
| | - Marie-Theres Bayer
- Department of Pediatrics, Harvard Medical School, and.,Division of Gastroenterology, Boston Children's Hospital, Boston, MA 02115
| | - Scott B Snapper
- Department of Pediatrics, Harvard Medical School, and.,Division of Gastroenterology, Boston Children's Hospital, Boston, MA 02115.,Harvard Digestive Disease Center, Harvard Medical School, Boston, MA 02115
| | - Steen H Hansen
- Department of Pediatrics, Harvard Medical School, and.,Division of Gastroenterology, Boston Children's Hospital, Boston, MA 02115
| | - Jay R Thiagarajah
- Department of Pediatrics, Harvard Medical School, and.,Division of Gastroenterology, Boston Children's Hospital, Boston, MA 02115.,Harvard Digestive Disease Center, Harvard Medical School, Boston, MA 02115
| | - Wolfram Goessling
- Harvard Stem Cell Institute, Cambridge, MA 02138.,Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115.,Division of Gastroenterology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114
| | - Wayne I Lencer
- Department of Pediatrics, Harvard Medical School, and.,Division of Gastroenterology, Boston Children's Hospital, Boston, MA 02115.,Harvard Digestive Disease Center, Harvard Medical School, Boston, MA 02115
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40
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Anderson DM, Sheedlo MJ, Jensen JL, Lacy DB. Structural insights into the transition of Clostridioides difficile binary toxin from prepore to pore. Nat Microbiol 2019; 5:102-107. [PMID: 31712627 PMCID: PMC6925320 DOI: 10.1038/s41564-019-0601-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Accepted: 10/03/2019] [Indexed: 11/28/2022]
Affiliation(s)
- David M Anderson
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA.,The Veterans Affairs Tennessee Valley Healthcare System, Nashville, TN, USA
| | - Michael J Sheedlo
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA.,The Veterans Affairs Tennessee Valley Healthcare System, Nashville, TN, USA
| | - Jaime L Jensen
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - D Borden Lacy
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA. .,The Veterans Affairs Tennessee Valley Healthcare System, Nashville, TN, USA.
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41
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Omersa N, Podobnik M, Anderluh G. Inhibition of Pore-Forming Proteins. Toxins (Basel) 2019; 11:E545. [PMID: 31546810 PMCID: PMC6784129 DOI: 10.3390/toxins11090545] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 08/27/2019] [Accepted: 09/10/2019] [Indexed: 12/16/2022] Open
Abstract
Perforation of cellular membranes by pore-forming proteins can affect cell physiology, tissue integrity, or immune response. Since many pore-forming proteins are toxins or highly potent virulence factors, they represent an attractive target for the development of molecules that neutralize their actions with high efficacy. There has been an assortment of inhibitors developed to specifically obstruct the activity of pore-forming proteins, in addition to vaccination and antibiotics that serve as a plausible treatment for the majority of diseases caused by bacterial infections. Here we review a wide range of potential inhibitors that can specifically and effectively block the activity of pore-forming proteins, from small molecules to more specific macromolecular systems, such as synthetic nanoparticles, antibodies, antibody mimetics, polyvalent inhibitors, and dominant negative mutants. We discuss their mechanism of inhibition, as well as advantages and disadvantages.
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Affiliation(s)
- Neža Omersa
- Department of Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana, Slovenia.
| | - Marjetka Podobnik
- Department of Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana, Slovenia.
| | - Gregor Anderluh
- Department of Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana, Slovenia.
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42
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Exploring the Nature of Cationic Blocker Recognition by the Anthrax Toxin Channel. Biophys J 2019; 117:1751-1763. [PMID: 31587826 DOI: 10.1016/j.bpj.2019.08.041] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 07/11/2019] [Accepted: 08/05/2019] [Indexed: 01/20/2023] Open
Abstract
Obstructing conductive pathways of the channel-forming toxins with targeted blockers is a promising drug design approach. Nearly all tested positively charged ligands have been shown to reversibly block the cation-selective channel-forming protective antigen (PA63) component of the binary anthrax toxin. The cationic ligands with more hydrophobic surfaces, particularly those carrying aromatic moieties, inhibited PA63 more effectively. To understand the physical basis of PA63 selectivity for a particular ligand, detailed information is required on how the blocker structural elements (e.g., positively charged and aromatic groups) influence the molecular kinetics of the blocker/channel binding reactions. In this study, we address this problem using the high-resolution single-channel planar lipid bilayer technique. Several structurally distinct cationic blockers, namely per-6-S-(3-amino) propyl-β-cyclodextrin, per-6-S-(3-aminomethyl) benzyl-α-cyclodextrin, per-6-S-(3-aminomethyl) benzyl-β-cyclodextrin, per-6-S-(3-aminomethyl) benzyl-γ-cyclodextrin, methyltriphenylphosphonium ion, and G0 polyamidoamine dendrimer are tested for their ability to inhibit the heptameric and octameric PA63 variants and PA63F427A mutant. The F427 residues form a hydrophobic constriction region inside the channel, known as the "ϕ-clamp." We show that the cationic blockers interact with PA63 through a combination of forces. Analysis of the binding reaction kinetics suggests the involvement of cation-π, Coulomb, and salt-concentration-independent π-π or hydrophobic interactions in the cationic cyclodextrin binding. It is possible that these blockers bind to the ϕ-clamp and are also stabilized by the Coulomb interactions of their terminal amino groups with the water-exposed negatively charged channel residues. In PA63F427A, only the suggested Coulomb component of the cyclodextrin interaction remains. Methyltriphenylphosphonium ion and G0 polyamidoamine dendrimer, despite being positively charged, interact primarily with the ϕ-clamp. We also show that seven- and eightfold symmetric cyclodextrins effectively block the heptameric and octameric forms of PA63 interchangeably, adding flexibility to the earlier formulated blocker/target symmetry match requirement.
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43
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Roderer D, Raunser S. Tc Toxin Complexes: Assembly, Membrane Permeation, and Protein Translocation. Annu Rev Microbiol 2019; 73:247-265. [DOI: 10.1146/annurev-micro-102215-095531] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Tc toxin complexes are virulence factors of many bacteria, including insect and human pathogens. Tc toxins are composed of three subunits that act together to perforate the host membrane, similar to a syringe, and translocate toxic enzymes into the host cell. The reactions of the toxic enzymes lead to deterioration and ultimately death of the cell. We review recent high-resolution structural and functional data that explain the mechanism of action of this type of bacterial toxin at an unprecedented level of molecular detail. We focus on the steps that are necessary for toxin activation and membrane permeation. This is where the largest conformational transitions appear. Furthermore, we compare the architecture and function of Tc toxins with those of anthrax toxin and vertebrate teneurin.
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Affiliation(s)
- Daniel Roderer
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, 44227 Dortmund, Germany;,
| | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, 44227 Dortmund, Germany;,
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44
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Self-conjugated protective antigen elicits strong and durable protective antibody response against anthrax. Int J Biol Macromol 2019; 137:790-800. [DOI: 10.1016/j.ijbiomac.2019.06.233] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2019] [Revised: 06/28/2019] [Accepted: 06/28/2019] [Indexed: 02/01/2023]
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Development of a novel chimeric PA-LF antigen of Bacillus anthracis, its immunological characterization and evaluation as a future vaccine candidate in mouse model. Biologicals 2019; 61:38-43. [PMID: 31416791 DOI: 10.1016/j.biologicals.2019.07.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 07/28/2019] [Accepted: 07/29/2019] [Indexed: 02/07/2023] Open
Abstract
Tremendous efforts are being made to develop an anthrax vaccine with long term protection. The main component of traditional anthrax vaccine is protective antigen (PA) with the trace amount of other proteins and bacterial components. In this study, we developed a recombinant PA-LF chimera antigen of Bacillus anthracis by fusing the PA domain 2-4 with lethal factor (LF) domain 1 and evaluated its protective potential against B. anthracis in mouse model. The anti-PA-LF chimera serum reacted with both PA and LF antigen, individually. The chimera elicited a strong antibody titer in mice with predominance of IgG1 isotype followed by IgG2b, IgG2a and IgG3. Cytokines were assessed in splenocytes of immunized mice and a significant up-regulation in the expression of IL-4, IL-10, IFN-γ and TNF-α was observed. The PA-LF chimera immunized mice exhibited 80% survival after challenge with virulent spores of B. anthracis. Pathological studies showed normal architecture in vital organs (spleen, lung, liver and kidney) of recovered immunized mice on 20 DPI after spore challenge. These findings suggested that PA-LF chimera of B. anthracis elicited good humoral as well as cell mediated immune response in mice, and thus, can be a potent vaccine candidate against anthrax.
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Kondakova OA, Nikitin NA, Evtushenko EA, Ryabchevskaya EM, Atabekov JG, Karpova OV. Vaccines against anthrax based on recombinant protective antigen: problems and solutions. Expert Rev Vaccines 2019; 18:813-828. [PMID: 31298973 DOI: 10.1080/14760584.2019.1643242] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Introduction: Anthrax is a dangerous bio-terror agent because Bacillus anthracis spores are highly resilient and can be easily aerosolized and disseminated. There is a threat of deliberate use of anthrax spores aerosol that could lead to serious fatal diseases outbreaks. Existing control measures against inhalation form of the disease are limited. All of this has provided an impetus to the development of new generation vaccines. Areas сovered: This review is devoted to challenges and achievements in the design of vaccines based on the anthrax recombinant protective antigen (rPA). Scientific databases have been searched, focusing on causes of PA instability and solutions to this problem, including new approaches of rPA expression, novel rPA-based vaccines formulations as well as the simultaneous usage of PA with other anthrax antigens. Expert opinion: PA is a central anthrax toxin component, playing a key role in the defense against encapsulated and unencapsulated strains. Subunit rPA-based vaccines have a good safety and protective profile. However, there are problems of PA instability that are greatly enhanced when using aluminum adjuvants. New adjuvant compositions, dry formulations and resistant to proteolysis and deamidation mutant PA forms can help to handle this issue. Devising a modern anthrax vaccine requires huge efforts.
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Affiliation(s)
- Olga A Kondakova
- a Department of Virology, Faculty of Biology, Lomonosov Moscow State University , Moscow , Russian Federation
| | - Nikolai A Nikitin
- a Department of Virology, Faculty of Biology, Lomonosov Moscow State University , Moscow , Russian Federation
| | - Ekaterina A Evtushenko
- a Department of Virology, Faculty of Biology, Lomonosov Moscow State University , Moscow , Russian Federation
| | - Ekaterina M Ryabchevskaya
- a Department of Virology, Faculty of Biology, Lomonosov Moscow State University , Moscow , Russian Federation
| | - Joseph G Atabekov
- a Department of Virology, Faculty of Biology, Lomonosov Moscow State University , Moscow , Russian Federation
| | - Olga V Karpova
- a Department of Virology, Faculty of Biology, Lomonosov Moscow State University , Moscow , Russian Federation
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47
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Vance TDR, Guo S, Assaie-Ardakany S, Conroy B, Davies PL. Structure and functional analysis of a bacterial adhesin sugar-binding domain. PLoS One 2019; 14:e0220045. [PMID: 31335890 PMCID: PMC6650083 DOI: 10.1371/journal.pone.0220045] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Accepted: 07/08/2019] [Indexed: 01/17/2023] Open
Abstract
Bacterial adhesins attach their hosts to surfaces through one or more ligand-binding domains. In RTX adhesins, which are localized to the outer membrane of many Gram-negative bacteria via the type I secretion system, we see several examples of a putative sugar-binding domain. Here we have recombinantly expressed one such ~20-kDa domain from the ~340-kDa adhesin found in Marinobacter hydrocarbonoclasticus, an oil-degrading bacterium. The sugar-binding domain was purified from E. coli with a yield of 100 mg/L of culture. Circular dichroism analysis showed that the protein was rich in beta-structure, was moderately heat resistant, and required Ca2+ for proper folding. A crystal structure was obtained in Ca2+ at 1.2-Å resolution, which showed the presence of three Ca2+ ions, two of which were needed for structural integrity and one for binding sugars. Glucose was soaked into the crystal, where it bound to the sugar's two vicinal hydroxyl groups attached to the first and second (C1 and C2) carbons in the pyranose ring. This attraction to glucose caused the protein to bind certain polysaccharide-based column matrices and was used in a simple competitive binding assay to assess the relative affinity of sugars for the protein's ligand-binding site. Fucose, glucose and N-acetylglucosamine bound most tightly, and N-acetylgalactosamine hardly bound at all. Isothermal titration calorimetry was used to determine specific binding affinities, which lie in the 100-μM range. Glycan arrays were tested to expand the range of ligand sugars assayed, and showed that MhPA14 bound preferentially to branched polymers containing terminal sugars highlighted as strong binders in the competitive binding assay. Some of these binders have vicinal hydroxyl groups attached to the C3 and C4 carbons that are sterically equivalent to those presented by the C1 and C2 carbons of glucose.
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Affiliation(s)
- Tyler D. R. Vance
- Department of Biomedical and Molecular Science, Queen’s University, Kingston, Ontario, Canada
| | - Shuaiqi Guo
- Department of Biomedical and Molecular Science, Queen’s University, Kingston, Ontario, Canada
| | - Shayan Assaie-Ardakany
- Department of Biomedical and Molecular Science, Queen’s University, Kingston, Ontario, Canada
| | - Brigid Conroy
- Department of Biomedical and Molecular Science, Queen’s University, Kingston, Ontario, Canada
| | - Peter L. Davies
- Department of Biomedical and Molecular Science, Queen’s University, Kingston, Ontario, Canada
- * E-mail:
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48
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Yamini G, Nestorovich EM. Multivalent Inhibitors of Channel-Forming Bacterial Toxins. Curr Top Microbiol Immunol 2019; 406:199-227. [PMID: 27469304 PMCID: PMC6814628 DOI: 10.1007/82_2016_20] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Rational design of multivalent molecules represents a remarkable modern tool to transform weak non-covalent interactions into strong binding by creating multiple finely-tuned points of contact between multivalent ligands and their supposed multivalent targets. Here, we describe several prominent examples where the multivalent blockers were investigated for their ability to directly obstruct oligomeric channel-forming bacterial exotoxins, such as the pore-forming bacterial toxins and B component of the binary bacterial toxins. We address problems related to the blocker/target symmetry match and nature of the functional groups, as well as chemistry and length of the linkers connecting the functional groups to their multivalent scaffolds. Using the anthrax toxin and AB5 toxin case studies, we briefly review how the oligomeric toxin components can be successfully disabled by the multivalent non-channel-blocking inhibitors, which are based on a variety of multivalent scaffolds.
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Affiliation(s)
- Goli Yamini
- Department of Biology, The Catholic University of America, Washington, D.C., 20064, USA
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49
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Stiles BG. Clostridial Binary Toxins: Basic Understandings that Include Cell Surface Binding and an Internal "Coup de Grâce". Curr Top Microbiol Immunol 2019; 406:135-162. [PMID: 27380267 DOI: 10.1007/82_2016_11] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Clostridium species can make a remarkable number of different protein toxins, causing many diverse diseases in humans and animals. The binary toxins of Clostridium botulinum, C. difficile, C. perfringens, and C. spiroforme are one group of enteric-acting toxins that attack the actin cytoskeleton of various cell types. These enterotoxins consist of A (enzymatic) and B (cell binding/membrane translocation) components that assemble on the targeted cell surface or in solution, forming a multimeric complex. Once translocated into the cytosol via endosomal trafficking and acidification, the A component dismantles the filamentous actin-based cytoskeleton via mono-ADP-ribosylation of globular actin. Knowledge of cell surface receptors and how these usurped, host-derived molecules facilitate intoxication can lead to novel ways of defending against these clostridial binary toxins. A molecular-based understanding of the various steps involved in toxin internalization can also unveil therapeutic intervention points that stop the intoxication process. Furthermore, using these bacterial proteins as medicinal shuttle systems into cells provides intriguing possibilities in the future. The pertinent past and state-of-the-art present, regarding clostridial binary toxins, will be evident in this chapter.
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Affiliation(s)
- Bradley G Stiles
- Biology Department, Wilson College, Chambersburg, PA, 17201, USA.
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Morton CJ, Sani MA, Parker MW, Separovic F. Cholesterol-Dependent Cytolysins: Membrane and Protein Structural Requirements for Pore Formation. Chem Rev 2019; 119:7721-7736. [DOI: 10.1021/acs.chemrev.9b00090] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Craig J. Morton
- Department of Biochemistry and Molecular Biology, Bio21 Institute, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Marc-Antoine Sani
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Michael W. Parker
- Department of Biochemistry and Molecular Biology, Bio21 Institute, University of Melbourne, Parkville, Victoria 3010, Australia
- St. Vincent’s Institute of Medical Research, Fitzroy, Victoria 3065, Australia
| | - Frances Separovic
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, Victoria 3010, Australia
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